After having looked at your source, it would seem ALL of the JavaScript and CSS (include) files are missing, which should have been included in your header. This usually happens when the wp_head(); tag is missing from your theme file.

The stuff needed to generate the maps and markers is fine, but all of the included files for Google maps, jQuery and so forth is not there, which is a major problem.

Can you confirm if the theme you are using has wp_head in the header?

Need to dash off now for the day, but will sign-up at your site tomorrow and take a look behind the scenes for you if you are still having the same problem by then…